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The maximizers sound like the most likely explanation to me.<br><br>
That being said, one point in the diagnosis that I would still do is to
Megger test the wiring while the wiring is in the conduit. If I
understood correctly, the wiring was tested while out of the conduit.
This can miss the problem since a wire can fault against the wall of a
conduit and find nothing to fault to when out of the pipe. <br><br>
At this point, I'd bet on the Tigo Maximizers being the most likely
culprit. <br><br>
At 12:38 PM 9/10/2016, you wrote:<br>
<blockquote type=cite class=cite cite="">Yes this is an interesting case,
as are the debug suggestions given. The wire pairs working out of metal
conduit point strongly at either ground faulting or inductive coupling.
You seem to have eliminated the obvious wiring issues like polarity and
grounding. Since you have a working system next door and you are already
putting in the hard work of swapping inverters and wires, it is worth
trying to swap the inverter from that working system with the non-working
one. This would either indict or eliminate the inverter as the culprit.
<br><br>
It is worth noting that the TrinaSmart modules with Tigo Maximizers are
quite capable of being the source of the problem. They attempt to do MPPT
at the module level, and can conflict with the inverter's attempts at
MPPT. We have had problems with other inverter brands to the extent that
power production was impaired, although not as bad as your complete
shutdown. It was necessary to use the inverter setup options to shut off
MPPT. If Solectria allows this it is worth trying. <br>
Also I have had problems with Tigo Maximizers on mismatched strings
shutting down one string completely to "maximize" others. You
may be seeing the effect of communication problems from the maximizer
wireless controller. Try disabling them if possible by shutting down
their controller with its secret software.<br>
I'm guessing that plain dumb modules with a plain dumb inverter would not
be suffering this shutdown problem. Something in your system is too smart
for your own good.<br><br>
Don Barch<br>
Energy Solar<br><br>
<dl>
<dd>-------- Original Message --------<br><br>
<br>
<dd>-----Original Message-----<br>
<dd>From: RE-wrenches
[<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org">
mailto:re-wrenches-bounces@lists.re-wrenches.org</a>] On<br>
<dd>Behalf Of Matt Partymiller<br>
<dd>Sent: Wednesday, September 07, 2016 4:46 PM<br>
<dd>To:
<a href="mailto:re-wrenches@lists.re-wrenches.org">
re-wrenches@lists.re-wrenches.org</a><br>
<dd>Subject: [RE-wrenches] Troubleshooting Stumper - Homerun Interference
in<br>
<dd>Conduit/Inverter Turning Off/On Rapidly<br><br>
<dd>Wrenches,<br><br>
<dd>One of our systems is having an issue I have not encountered before
where<br>
<dd>the inverter switches between nighttime mode and interconnection
every few<br>
<dd>seconds. I am hoping for some technical wisdom from the
community.<br><br>
<dd>We have an array of 20 TrinaSmart modules in two strings of 10. The
array<br>
<dd>is connected to a Solectria 3.8 kW inverter. The conduit run is
simple, all<br>
<dd>four homerun wires (#10 PVwire) in 1" EMT down to the proximity
of the<br>
<dd>Solectria inverter where the conduit switches to 1" LFMC before
entering the<br>
<dd>inverter. The run is about 20', straight down the side of the wall
before<br>
<dd>hitting the inverter. A 600V jacketed communications wire was also in
the<br>
<dd>conduit but has since been removed and run separately.<br><br>
<dd>Our inverter is starting up, running for a few seconds, giving a low
voltage<br>
<dd>error, briefly showing nighttime mode, then going into startup mode
again.<br>
<dd>Solectria was gracious enough to send us a new inverter but we have
the<br>
<dd>exact same issue. They tell us their error codes (266, 274) indicate
0<br>
<dd>volts. The transition between low voltage error and startup is
almost<br>
<dd>instant. Basically we have 20 seconds of start up, 5 seconds of run,
5<br>
<dd>seconds of error then repeat. This is not a grid problem, the
identical<br>
<dd>system next door works fine.<br><br>
<dd>In the process of troubleshooting, our technician pulled all four
homerun<br>
<dd>wires out of our conduit and meggered them. They all tested fine so
he<br>
<dd>connected to the inverter. The inverter worked fine. The
technician<br>
<dd>verified grounding of the array and conduit, pulled new homeruns
back<br>
<dd>through the conduit, and reconnected to the inverter. He had the same
error<br>
<dd>as before.<br><br>
<dd>He connected each string separately to the inverter by removing the
string<br>
<dd>fuses. Either string will operate fine independently. With string one
in<br>
<dd>conduit and either homerun of string two in conduit (but not both)
the<br>
<dd>inverter operates fine. With string two in conduit but string one
outside<br>
<dd>of conduit, the inverter does not operate.<br><br>
<dd>I was certain the error had something to do with homerun roof wiring
so I<br>
<dd>went out with the technician and removed and checked pretty much
every<br>
<dd>module. Everything appears fine, all connections solid, all homeruns
have<br>
<dd>been remade at least once at this point. Now I am stumped and lack
the<br>
<dd>technical knowledge to diagnose the problem. I would be extremely
grateful<br>
<dd>if an esteemed wrench can provide technical support/advice.<br><br>
<dd>Thanks,<br><br>
<dd>Matt<br><br>
<br><br>
<br>
<dd>Matthew Partymiller<br>
<dd>Solar Energy Solutions LLC<br>
<dd>(877) 312-7456<br>
<dd><a href="mailto:matt@solar-energy-solutions.com">
matt@solar-energy-solutions.com</a><br><br>
<br>
<dd>_______________________________________________<br>
<dd>List sponsored by Redwood Alliance<br><br>
<br><br>
</dl>_______________________________________________<br>
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